Get a good home inspection. If you get a chance to watch the Canadian TV series "Holmes Inspection", consider doing it (it was on NetFlix last year, but I think it slipped off their list). Attend the inspection, and wear coveralls / be prepared to crawl around in the crawl space / attic with your inspector. Ask them to show you things as they find them, and explain what they've found. Learn as much about your new house going into the deal as you can.
Eventually, they'll come up with a report of items that should be repaired / replaced, and an estimate of the cost to repair / replace the issue in question. Use the total figure to negotiate the price from the seller. Example: the inspection shows there's $6,000 in repairs needed on the house (replacement of failed double-pane windows, dry-rot in the basement, etc) - you then ask the seller to either repair the damage, OR give you a $6,000 credit so you can get the items repaired with your own contractor. The point is the inspection figure is a negotiation tool - you have a $350 inspection report that can be leveraged to get a larger discount from the seller. Then, you get the items repaired, or repair them yourself.
The inspection may also find something major / structural that you're not comfortable with, or was undisclosed at the time of sale. If it's something serious that you simply don't feel comfortable dealing with, it gives you the leverage to walk away from the deal. Example: inspection shows the foundation has a major failure and/or the house has slipped off the foundation in one corner.
